CSI-5174 - Assignment 4: Protocol derivation

Given: November 12 - - Due: November 18 - - This will only count for 10 points - the purpose is to prepare yourself for some questions in the final exam that may be related to this topic

Design of a Taxi system

We consider a modified version (see below) of the taxi system described in the course notes. We assume that all sequencing between the different activities shown as arrows in the diagram are weak sequences. There are several cases of non-local choices (competing initiatives).

Part 1: Ignoring the competing initiatives (assuming that never both sides would take an initiative at the same time), use the protocol derivation approach described in the course notes to derive state machine behaviors for the three components: user, taxi and manager. You may assume that the system contains only one user, one taxi and one manager.

Question: Is it reasonable to assume (as stated above) that all sequencing between the different activities shown as arrows in the diagram are weak sequences ?

Part 2: Check the protocol obtained in Part 1 for competing initiatives (these are non-local choices that would give rise to unspecified receptions if queued message passing would be used - note the protocol derivation approach suggests pooled message reception) - you may do this intuitively or by performing reachability analysis. Identify the non-local choices.

Part 3: Use Gouda's method to resolve the non-local choices by adding suitable reception transitions. Does the obtained system work without problems ?